Momentum diffusion, decoherence, and drag force on a magnetic nanoparticle
Phys. Rev. A 114, 023716 – Published 17 August, 2026
DOI: https://doi.org/10.1103/zcxg-k9nn
Abstract
In this paper, we will provide a complete derivation of the decoherence rate for a magnetic nanoparticle in quantum superposition in the presence of the fluctuating electromagnetic field in a thermal background by using the fluctuation-dissipation theorem in the long-wavelength limit. The long-wavelength limit assumes that the superposition size is much smaller than the wavelength of the electromagnetic-field fluctuations. We will extend this computation to two diamagnetic nanoparticles kept in quantum superposition adjacent to each other. We will also show how the drag force on a single nanoparticle arises from external electromagnetic-field fluctuations and compare our results with those for the nanoparticle's dielectric properties.
